This invention relates to a mobile storage system, and more particularly to a passive safety arrangement for use in a mobile storage system.
A mobile storage system typically consists of a series of storage units that are movable on rails or the like toward and away from each other. Movement of the storage units is controlled so as to selectively create an aisle between an adjacent pair of storage units. When an aisle is created, a user enters the aisle to access an area of one or both of the storage units that form the aisle, such as to remove an object from one or more of the storage units or to place an object on or in one or more of the storage units. Mobile storage systems of this type are commonly available from a number of different manufacturers, including Spacesaver Corporation of Fort Atkinson, Wis.
A number of safety systems have been developed so as to ensure that an aisle is empty before the pair of storage units forming the aisle are closed in order to create an aisle between a different pair of storage units. In a typical configuration of a passive safety system, a series of cross-aisle sensors are positioned at spaced-apart locations throughout the length of each storage unit in an adjacent pair of storage units. The cross-aisle sensors are typically uniformly spaced a selected distance apart, e.g. on twelve inch centers, and act to sense the presence of a person or object in the aisle. The cross-aisle sensors are typically in the form of light beam emitters and receivers. The presence of a person or object in the path of one of the light beams prevents the light beam from reaching the receiver, which provides a signal to a controller that is interpreted to indicate the presence of a person or object in the aisle. In this manner, the controller is responsive to the signals so as to ensure that the adjacent storage units are not closed until the aisle between the storage units is clear of persons or objects.
In addition, prior art passive safety systems have employed a quadrature sensor at each entry or access point between adjacent mobile storage units. Each quadrature sensor typically includes a pair of light beams, which are sequentially blocked as a person or object enters or exits an aisle to indicate the direction of movement of a person or object into or out of the aisle. The quadrature sensor is typically placed at approximately knee level, which ensures that a person is not able to step over the light beams of the quadrature sensor when entering or exiting the aisle. The controller is responsive to signals from the both the quadrature sensors and the cross-aisle sensors, to ensure that adjacent storage units are not closed until it is determined that the aisle between the storage units clear and that every person or object that has entered that aisle has also exited the aisle.
While a passive safety system having the above-identified components is reliable and functions well, it involves certain drawbacks. For example, the cross-aisle sensors and the quadrature sensors are mounted to each storage unit in different locations, i.e. the cross-aisle sensors are low and close to the floor whereas the quadrature sensors are elevated above the floor. This requires separate mounting of the housings and other components of the different sensors. In addition, the cross-aisle sensors and the quadrature sensors require separate wiring. As a result, the number of parts involved in this configuration, in combination with the resulting assembly time and labor costs, increases the overall cost associated with manufacture of the storage units.
It is an object of the present invention to provide an improved passive safety system for use in a mobile storage system, which simplifies the construction and installation of cross-aisle sensors and quadrature sensors in the mobile storage units. It is another object of the invention to provide such an improved passive safety system which provides reliability in detecting the presence of persons or objects between adjacent mobile storage units and also senses direction of movement of persons or objects into or out of the aisle. A still further object of the invention is to provide a simplified and reliable method of sensing the presence of a person or object between adjacent mobile storage units and direction of movement of a person or object into or out of the aisle.
In accordance with a first aspect of the invention, a mobile storage system includes a number of storage units supported by a supporting surface, including at least a first storage unit that is movable toward and away from a second storage unit by operation of a drive arrangement to selectively create an aisle between the first and second storage units, in which the aisle is accessible from an end area. A sensing system detects the presence of persons or objects in the aisle and also detects the direction of movement of persons or objects into or out of the aisle. The sensing system includes a number of exit zone emitters and receivers located adjacent an end area of the first and second storage units that defines the end area of the aisle, and a number of inner emitters and receivers located along an inner area of the first and second storage units inwardly of the end area. The exit zone emitters and receivers and the inner emitters and receivers are located at generally the same elevation adjacent and above the supporting surface. In one form, each of the storage units includes a carriage and a storage member secured to the carriage. The carriage is movable relative to the supporting surface, and the exit zone emitters and receivers and the inner emitters and receivers are located on the carriage.
In accordance with another aspect of the invention, a mobile storage system includes presence and direction sensing means carried by the storage units for detecting the presence of persons or objects in the aisle and for detecting the direction of movement of persons or objects into or out of the aisle. The presence and direction sensing means includes an end sensing section, or exit zone, located adjacent at least an end area of the first and second storage units that defines the end area of the aisle, and an interior sensing section located inwardly of the end area. The end sensing section and the interior sensing section are interconnected with each storage unit via a sensor housing carried by the storage unit and located above the supporting surface. Each storage unit includes a carriage and a storage member secured to the carriage, and the sensor housing is located on the carriage. The end sensing section and the interior sensing section are located at generally the same elevation adjacent and above the supporting surface.
Another aspect of the invention contemplates a method of operating a mobile storage system that includes adjacent first and second storage units supported by a supporting surface. This aspect of the invention includes detecting the location of a person or object within an aisle between the first and second storage units adjacent an end area of the first and second storage units and along an inner area of the first and second storage units inwardly of the end area. The act of detecting the location of a person or object within an aisle is carried out so as to detect both the presence of the person or object and the direction of movement of the person or object, both of which are carried out at generally the same elevation adjacent and above the supporting surface, preferably using a series of emitters and receivers carried by the storage unit.
The invention also contemplates an improvement in a carriage for supporting a storage member for use in a mobile storage system in which the carriage is movable by operation of a drive arrangement relative to a supporting surface. In accordance with this aspect of the invention, the carriage includes an outwardly facing side area that is adapted to face an aisle formed in the mobile storage system when the carriage is positioned in spaced apart relationship relative to an adjacent storage member. A presence and direction detecting sensing system is interconnected with the outwardly facing side area, and includes a sensor housing having a series of exit zone sensors located adjacent at least an end area of the carriage, and a series of inner sensors located along at least an intermediate area of carriage inwardly of the end area. The sensor housing and the sensors are configured relative to the carriage so as to be at generally the same elevation adjacent and above the supporting surface when the carriage is positioned on the supporting surface. A power supply and communication arrangement is interconnected with the sensor housing, and is configured to supply power to the sensors and to communicate signals from the sensors to a controller.
The invention also contemplates a method of constructing a carriage for supporting a storage member for use in a mobile storage system, substantially in accordance with the foregoing summary.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.